Photographers often have two or more camera bodies in use simultaneously when photographing an event. This is done to have more capabilities, and faster access to different capabilities, than can be provided by a single camera/lens system. As shooting conditions change, the photographer can switch among multiple camera bodies to respond quickly to widely changing requirements. For example, a sports photographer may have a wide-angle lens mounted on one body, and a telephoto lens mounted on a second body. Having these two camera setups allows the photographer to capture action that occurs nearby using the camera body equipped with the wide-angle lens, and action that occurs a distance using the camera body equipped with the telephoto lens. This switch can be made without losing the time needed to change camera lenses.
In practice, a significant challenge to using more than one camera body simultaneously is keeping multiple cameras set to the desired operational settings. As shooting conditions change, photographers often change settings on the camera to respond to those changing conditions. For example, if lighting levels drop significantly, the photographer may increase ISO sensitivity. Changing settings on the camera in use at the moment will allow that camera to get the desired results—but such changes made to one camera body will not affect the other cameras the photographer is using to photograph the event. When the photographer switches to a second camera, the photographer will have to replicate the operational setting changes on the second camera. Replicating these changes on the second camera costs the photographer valuable time, which may cause the photographer to miss getting important photographs of the event. In addition, the act of replicating such operational settings introduces the opportunity for human error, which could result in the use of incorrect camera settings on the second camera, and thus poor quality, or even ruined, photographs taken on the second camera.